Shorted rotating diode protection for synchronous machines

Abstract

An assembly according to an embodiment of the present disclosure includes, among other things, a synchronous machine including a rotating portion and a stationary portion, the rotating portion including at least one rotating diode coupled to a field winding, and the stationary portion including a stator winding and an exciter winding. A control unit includes a first gate and a second gate. The exciter winding is connected in series to the first gate and the second gate during a first operating mode to energize the exciter winding. The exciter winding is electrically connected in series to a first gate but is electrically disconnected from the second gate in a second, different operating mode to electrically disconnect the exciter winding from an exciter energy source. A method of operating a synchronous machine is also disclosed.

What is claimed is: 
     
       1. An assembly comprising:
 a synchronous machine including a rotating portion and a stationary portion, the rotating portion including at least one rotating diode coupled to a field winding, and the stationary portion including a stator winding and an exciter winding; 
 a control unit including a first gate and a second gate; 
 wherein the exciter winding is connected in series to the first gate and the second gate during a first operating mode to energize the exciter winding; and 
 wherein the exciter winding is electrically connected in series to the first gate but is electrically disconnected from the second gate in a second, different operating mode to electrically disconnect the exciter winding from an exciter energy source; 
 wherein the control unit includes a first diode and a second diode; 
 wherein the first diode and the second diode are electrically disconnected from the exciter winding during the first operating mode; 
 wherein the second diode is electrically connected to the exciter winding, and the first diode is electrically disconnected from the exciter winding during the second operating mode; 
 wherein the first diode and the second diode are electrically connected in series to the exciter winding during a third, different operating mode; 
 wherein the exciter energy source is electrically disconnected from the exciter winding in the third operating mode; 
 wherein the exciter energy source is electrically disconnected from the exciter winding in response to closing the first gate and opening the second gate during the second operating mode; 
 wherein the control unit includes a bridge rectifier that electrically connects the exciter winding to the exciter energy source during the first operating mode; 
 wherein the exciter winding is electrically in parallel with the bridge rectifier and with a capacitor during the first operating mode; 
 wherein the capacitor and the bridge rectifier are electrically disconnected from the exciter winding during the second operating mode; 
 wherein the exciter energy source is a three-phase generator including phase lines each electrically coupled to a respective pair of diodes of the bridge rectifier; 
 wherein the first gate and the second gate are transistors; 
 wherein the control unit includes a third gate electrically connected in series with the first gate, a resistance and a third diode during the second operating mode; 
 wherein the exciter winding is electrically connected in parallel with the third gate, the resistance and the third diode during the second operating mode; and 
 wherein the third gate is electrically disconnected from the exciter winding during the first operating mode and during the third operating mode. 
 
     
     
       2. The assembly as recited in  claim 1 , wherein circuitry between the exciter energy source and the exciter winding is free of any transient voltage suppression diodes. 
     
     
       3. The assembly as recited in  claim 1 , wherein the control unit is operable to simultaneously communicate a first gate signal to the first gate and a second, different gate signal to the second gate. 
     
     
       4. The assembly as recited in  claim 3 , wherein the control unit is operable to hold closed the first gate during the second operating mode, and is operable to hold open the second gate during the second operating mode. 
     
     
       5. The assembly as recited in  claim 4 , wherein the second operating mode relates to a shorted rotating diode event caused by the at least one rotating diode. 
     
     
       6. The assembly as recited in  claim 1 , wherein the second operating mode relates to a shorted rotating diode event caused by the at least one rotating diode. 
     
     
       7. A synchronous machine comprising:
 a rotating portion including at least one rotating diode coupled to a field winding; 
 a stationary portion including a stator winding, an exciter winding, a bridge rectifier coupled to a permanent magnet generator, a capacitor, and a plurality of nodes, the plurality of nodes including a first node, a second node, a third node and a fourth node; 
 a control unit including a first gate, a second gate, a third gate, a first diode, a second diode, and a third diode; 
 wherein components of the first node consist of the bridge rectifier, the capacitor, a drain terminal of the first gate, and a cathode of the second diode; 
 wherein components of the second node comprise a first terminal of the exciter winding, a cathode of the first diode, a source terminal of the first gate, and a drain terminal of the third gate; 
 wherein components of the third node comprise a second terminal of the exciter winding, an anode of the second diode, a drain terminal of the second gate, and a cathode of the third diode; 
 wherein components of the fourth node comprise the bridge rectifier, the capacitor, a source terminal of the second gate, and an anode of the first diode; 
 wherein the exciter winding is electrically connected in series to the first gate and the second gate during a first operating mode to energize the exciter winding; 
 wherein the exciter winding is electrically connected in series to the first gate, but is electrically disconnected from the second gate during a second, different operating mode to electrically disconnect the exciter winding from the permanent magnet generator; 
 wherein the first diode and the second diode are electrically connected in series to the exciter winding during a third, different mode; 
 wherein the third gate is electrically connected in series with the first gate, a resistance and the third diode during the second operating mode; 
 wherein the exciter winding is electrically connected in parallel with the third gate, the resistance and the third diode during the second operating mode; and 
 wherein the third gate is electrically disconnected from the exciter winding during the first operating mode and during the third operating mode. 
 
     
     
       8. A method of operating a synchronous machine, comprising:
 closing first and second gates to energize an exciter winding in series between the first and second gates in a first operating mode; 
 opening the second gate, but closing the first gate to electrically disconnect to the exciter winding from a rectifier in a second operating mode in response to a shorted rotating diode event, wherein the rectifier is coupled to an exciter energy source; 
 opening the first and second gates in a third operating mode to electrically disconnect the exciter winding from the exciter energy source; 
 wherein a first diode and a second diode are electrically connected in series to the exciter winding during the third operating mode; 
 closing a third gate in the second operating mode such that the third gate is electrically connected in series with the first gate, a resistance and a third diode; 
 wherein the exciter winding is electrically connected in parallel with the third gate, the resistance and the third diode during the second operating mode; and 
 wherein the third gate is electrically disconnected from the exciter winding during the first operating mode and during the third operating mode. 
 
     
     
       9. The method as recited in  claim 8 , wherein the first gate and the second gate are transistors. 
     
     
       10. The method as recited in  claim 9 , wherein circuitry between the exciter energy source and the exciter winding is free of any transient voltage suppression diodes. 
     
     
       11. The method as recited in  claim 9 , wherein phase lines of the exciter energy source are each coupled to a respective pair of diodes of the rectifier. 
     
     
       12. The method as recited in  claim 8 , wherein the step of closing the first and second gates includes electrically connecting in parallel a capacitor with the exciter winding and the rectifier. 
     
     
       13. The method as recited in  claim 12 , wherein the step of opening the second gate includes electrically connecting the first diode in series with the first gate and the exciter winding in the second operating mode.